The potency of volatile anesthetics and n-alkanes as agents of general anesthesia has been determined in Drosophila melanogaster. The correlation of potency with hydrophobicity and the absolute concentration required to achieve anesthetic effects are similar to those reported in higher organisms. Thus, Drosophila has been confirmed as a suitable model system for study of the mechanism of general anesthesia. Several mutants of the fruit fly that are altered in their response to halothane have been studied further. One mutant loses its anesthetic resistance upon decapitation while three other mutants retain resistance. This analysis highlights the anatomic complexity of the anesthetic response. In another study, wild-type and mutant intact flies have been assessed in a time-independent assay of the escape from a noxious stimulus. This tail-flick assay for fruit flies shows that each mutant locus differentially affects the response to different anesthetics. The result argues against the hypothesis that all anesthetics interact in identical manner with the anesthetic target.